The extracellular matrix proteins of the bones and teeth are key elements in the structue and metabolism of these tissues. The goal of this project is to study matrix proteins specific to each mineralizing skeletal tissue in order to understand their molecular structure and biological function. Analytical procedures (polyacrylamide gel electrophoresis, immunoblotting, specific dye-binding, RIA, ELISA, etc.) have been developed to quantitate the levels of bone specific noncollagenous proteins in (a) surgical specimens of bony tissue (osteonectin, bone sialoprotein and bone proteoglycan) and (b) serum (osteonectin). Changes in the noncollagenous protein profile with age and variety of bone (and tooth) diseases have been observed in man and several animal models. Recent developments in monclonal antibody production against osteonectin suggest that a family of related proteins similar to bone osteonectin may exist in tissue culture.